This book is the fourth of six that describe mysteries solved by the Black Widowers, based on a literary dining club he belonged to known as the Trap Door Spiders. It collects twelve stories by Asimov, together with a general introduction and an afterword following each story by the author. Nine of the stories were previously published; "The Driver," "The Wrong House" and "The Intrusion" are new to this collection. Each story involves the club…